Lens assembly

摘要

A lens assembly includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens, all of which are arranged in sequence from an object side to an image side along an optical axis. The first lens is with negative refractive power. The second, third, fourth and sixth lens are with refractive power. The fifth lens is with positive refractive power. The lens assembly satisfies: 0.078≦BFL/TTL≦0.4, 0.01≦f/TTL≦0.61, (Nd1+Nd2+Nd3+Nd4+Nd5+Nd6)/6<(Nd2+Nd3)/2 wherein BFL is a distance from an image side surface of the sixth lens to an image plane along the optical axis, TTL is a distance from the convex surface of the first lens to the image plane along the optical axis, f is an effective focal length of the lens assembly, and Nd1, Nd2, Nd3, Nd4, Nd5 and Nd6 are indexes of refraction of the first, second, third, fourth, fifth and sixth lenses.

主权项

1. A lens assembly comprising a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens, all of which are arranged in sequence from an object side to an image side along an optical axis, wherein:
the first lens is with negative refractive power and comprises a convex surface facing the object side and a concave surface facing the image side; the second lens is a biconcave lens and with negative refractive power; the third lens is with positive refractive power and comprises a convex surface facing the object side; the fourth lens is a meniscus lens with negative refractive power and comprises a convex surface facing the object side and a concave surface facing the image side; the fifth lens is with positive refractive power and comprises a convex surface facing the object side and a convex surface facing the image side; the sixth lens is with refractive power; and the lens assembly satisfies:
0.078≦BFL/TTL≦0.4,0.01≦f/TTL≦0.61,(Nd1+Nd2+Nd3+Nd4+Nd5+Nd6)/6<(Nd2+Nd3)/2 wherein BFL is a distance from an image side surface of the sixth lens to an image plane along the optical axis, TTL is a distance from the convex surface of the first lens to the image plane along the optical axis, f is an effective focal length of the lens assembly, Nd1 is an index of refraction of the first lens, Nd2 is an index of refraction of the second lens, Nd3 is an index of refraction of the third lens, Nd4 is an index of refraction of the fourth lens, Nd5 is an index of refraction of the fifth lens and Nd6 is an index of refraction of the sixth lens.